Symantec has seen another round of a ham-fisted but surprisingly successful attack that targets Facebook users hoping to break into their friends' accounts.

The seed of the scam is a video on Facebook that claims to offer a tool for obtaining login credentials for friends' accounts. Instead, it hacks the person's own account, said Satnam Narang, security response manager for Symantec, in a blog post.

The video directs potential victims to a document on Google Drive that contains a piece of JavaScript code. Users are instructed to paste the code in their browser's console window -- a feature used by developers -- and execute it.

If they do, their Facebook account is hijacked and used to "like" other pages and follow lists, which drives up the illusion of popularity of those pages.

This type of scam has been around since 2011, Narang wrote. Some of the words in the JavaScript code dating from that time suggest the authors may have been Turkish. The latest iteration, spotted last week in India, was likely adapted by scammers in that country.

Despite its dependence on compliant victims, the scam has been surprisingly successful. It was used earlier this year to inflate the "like" count on some pages by 50,000 to 100,000, Narang wrote.

The type of attack is known as "self cross-site scripting," where the user is tricked into running the malicious code themselves rather than finding it on a hacked website.

Facebook has warned against the type of attack and advised that it "gently disables" browser console windows. The social network allows people to re-enable the console, but the warning message it displays suggests it would rather you didn't: "Allow my account to be hijacked if I paste malicious JavaScript."

The whole idea that you can run a piece of code to hack friends' accounts should be enough to alert people that it's a scam, Narang wrote.

"Being able to hack someone's Facebook password by just pasting some code into your browser sounds way too easy and should signal that this is a scam," he wrote. "It's best to err on the side of caution and think twice before following instructions that ask you to paste code into your browser to hack passwords or unlock features on a website."